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Word Problems: Proportional Reasoning-1 | Mathematics Class 8- New NCERT (Ganita Prakash) PDF Download

Q1: The monthly income of A and B is in the ratio 3 : 4. If B’s income is ₹28,000, find A’s income.

Solution:
Ratio of A : B = 3 : 4
B’s income = ₹28,000Word Problems: Proportional Reasoning-1 | Mathematics Class 8- New NCERT (Ganita Prakash)

A’s income is ₹21,000.

Q2: A recipe requires flour and sugar in the ratio 5 : 2. If 1.4 kg sugar is used, how much flour is needed?

Solution:
Flour : Sugar = 5 : 2
Sugar = 1.4 kgWord Problems: Proportional Reasoning-1 | Mathematics Class 8- New NCERT (Ganita Prakash)

Q3: The ages of two friends are in the ratio 7 : 9. If the younger one is 21 years old, find the age of the elder.

Solution:
Ratio of ages = 7 : 9
Younger (7 parts) = 21Word Problems: Proportional Reasoning-1 | Mathematics Class 8- New NCERT (Ganita Prakash)The elder friend is 27 years old.

Q3: Two numbers are in the ratio 4 : 5. If their sum is 180, find the numbers.

Solution:
Let numbers = 4x and 5x
Sum = 180Word Problems: Proportional Reasoning-1 | Mathematics Class 8- New NCERT (Ganita Prakash)

The numbers are 80 and 100.

Q4: If 8 workers can build a wall in 15 days, in how many days will 12 workers build the same wall (assuming work efficiency is same)?

Solution:
This is an inverse proportion problem.Word Problems: Proportional Reasoning-1 | Mathematics Class 8- New NCERT (Ganita Prakash)

12 workers will build the wall in 10 days.

Q5: Ria and Tia share ₹840 in the ratio 4 : 3. Find each share.

Solution
Let Ria = 4x, Tia = 3x; total 4x + 3x = 840 ⇒ 7x = 840 ⇒ x = 120
Ria = 4x = ₹480, Tia = 3x = ₹360
Answer: ₹480 and ₹360

Q7: If 6 notebooks cost ₹162, how much will 14 notebooks cost?

Solution
Cost ∝ QuantityWord Problems: Proportional Reasoning-1 | Mathematics Class 8- New NCERT (Ganita Prakash)Word Problems: Proportional Reasoning-1 | Mathematics Class 8- New NCERT (Ganita Prakash)

Q8: Word Problems: Proportional Reasoning-1 | Mathematics Class 8- New NCERT (Ganita Prakash)

Q9: Word Problems: Proportional Reasoning-1 | Mathematics Class 8- New NCERT (Ganita Prakash)

Q10:Word Problems: Proportional Reasoning-1 | Mathematics Class 8- New NCERT (Ganita Prakash)

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FAQs on Word Problems: Proportional Reasoning-1 - Mathematics Class 8- New NCERT (Ganita Prakash)

1. What is proportional reasoning, and how is it applied in solving word problems?
Ans. Proportional reasoning involves understanding and using ratios and proportions to solve problems. It helps in determining relationships between quantities. For instance, if a recipe requires 2 cups of flour for 4 servings, proportional reasoning allows one to calculate how much flour is needed for 10 servings by setting up a proportion: 2 cups/4 servings = x cups/10 servings. Solving this gives x = 5 cups.
2. How can I identify proportional relationships in word problems?
Ans. To identify proportional relationships, look for keywords that suggest a constant ratio, such as "for every," "per," or "in relation to." Additionally, check if altering one quantity consistently affects another in a predictable manner. For example, if a car travels 60 miles in 1 hour, it will travel 120 miles in 2 hours, indicating a proportional relationship.
3. What strategies can I use to solve word problems involving proportions?
Ans. Effective strategies include: 1. Setting up a proportion equation based on the relationship described in the problem. 2. Cross-multiplying to solve for the unknown variable. 3. Checking your answer by substituting it back into the original scenario to ensure it makes sense. 4. Using visual aids like tables or graphs to organize information.
4. Can you give an example of a real-life situation where proportional reasoning is useful?
Ans. A common real-life application of proportional reasoning is in cooking. For instance, if a dish requires 3 tablespoons of sugar for a certain number of servings, and you wish to double the recipe, you would need 6 tablespoons of sugar. This use of proportions helps maintain the flavor and consistency of the dish.
5. What common mistakes should I avoid when solving proportional word problems?
Ans. Common mistakes include: 1. Misinterpreting the relationship between quantities, leading to incorrect setups. 2. Forgetting to simplify ratios before solving, which can complicate calculations. 3. Not checking if the final answer makes sense in the context of the problem. Always ensure that the units match and that the solution aligns with the given information.
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